While scientists have yet to figure out why this happens, they theorize that it has to do with a gene called MC1R. Redheads have a variant of this gene, which is what affects the process that alters their pigmentation in the first place (more on that in the video, too!). Experts suspect that MC1R expresses itself in a part of the brain that deals with sensation, which may lead to heightened sensitivity.

Take a look at the breakdown above, which is produced by the American Chemical Society and PBS Digital Studios, to learn more about the chemistry of being a redhead. It’s proof that this characteristic is just as rare and unique inside the body as it is on the outside.